Sartre was born in Paris, France. He studied philosophy at the École Normale Supérieure, an élite (high quality) education establishment. In 1929, Sartre graduated with a doctorate in philosophy. Sartre served in the French Army from 1929 to 1931.

In 1929 at the École Normale, he met Simone de Beauvoir, who studied at the Sorbonne. She went on to become a noted philosopher, writer, and feminist. The two became inseparable and lifelong companions. In 1938, Sartre wrote the novel called La Nausée (Nausea). This story explains the way of thinking of existentialism. Existentialism is a way of thinking about human freedom.

In 1939 Sartre was drafted into the French army. France was at war with Germany, because Germany had invaded France (World War II) Sartre was captured by German troops in 1940, and Sartre spent nine months as a prisoner of war in a camp. Sartre was released from the prison camp (jail) in 1941. Then Sartre began working as a teacher again. He made friends with other writers and thinkers such as Merleau-Ponty, Jean-Toussaint and Dominique Desanti, and Jean Kanapa.

In 1943, Sartre wrote a book about philosophy (ways of thinking) called L'Être et le Néant, which means Being and Nothingness. In this book, Sartre said that when people tried too hard to conform to the rules of society (or of their country), then people did not really make their own decisions.

In 1945, Sartre started a newspaper called Les Temps Modernes (Modern Times), which had articles about politics, art and literature. He also began writing a group of novels (stories) called Les Chemins de la Liberté (The Roads to Freedom). In 1946 Sartre wrote a book about philosophy (ways of thinking) called Existentialism is a Humanism, which explains existentialism.

In the 1950s and 1960s, Sartre became involved in politics. Sartre said that France should leave Algeria, a country where France had many soldiers. In the 1960s, Sartre said that the Vietnam War was bad. In 1960, he wrote the Critique de la raison dialectique (Critique of Dialectical Reason). In the 1960s, Sartre had many arguments with Louis Althusser, a man who also believed in communism.

Sartre died of oedema of the lung in 1980 in Paris. His body is buried in Cimetière du Montparnasse in Paris. His funeral was attended by 50,000 people.